1. Field of the Invention
The present invention relates to polyester yarn made from poly(trimethylene terephthalate) fibers. More particularly, the present invention relates to poly(trimethylene terephthalate) yarns fully oriented during the spinning process.
2. Background of the Invention
Synthetic fibers, such as polyester fibers, are well known in the textile industry for use in fabrics and garments. Such synthetic yarns are commonly made from polyethylene terephthalate fibers using known commercial processes. More recently, synthetic yarns from poly(trimethylene terephthalate) fibers are of interest. Because the two polymers have different properties, the base of knowledge related to spinning and drawing polyethylene terephthalate yarns is not directly applicable to poly(trimethylene terephthalate) yarns. However, the properties desirable in the end-product, i.e., the textile yarn or fabric, are often similar.
A xe2x80x9ctextile yarnxe2x80x9d must have certain properties, such as sufficiently high modulus and yield point, and sufficiently low shrinkage, so as to be suitable for use in textile processes, such as texturing, weaving and knitting. Feeder yarns, on the other hand, require further processing before they have the minimum properties for processing into textiles. Feeder yarns (also referred to as xe2x80x9cfeed yarnsxe2x80x9d herein) are typically prepared by melt-spinning partially oriented yarn filaments which are then drawn and heated to reduce shrinkage and to increase modulus.
Feed yarns do not have the properties required to make textile products without further drawing. The drawing process imparts higher orientation in the yarn filaments and imparts properties important for textile applications. One such property, boil off shrinkage (xe2x80x9cBOSxe2x80x9d), indicates the amount of shrinkage the yarn exhibits when exposed to high temperatures. Because feed yarns require additional processing, however, production throughput is low and production costs are high. Existing commercially available partially-oriented poly(trimethylene terephthalate) yarns are drawn or draw-textured before use in fabrics. It is therefore desirable to provide a xe2x80x9cdirect-usexe2x80x9d spun yarn which may be used to make textile products without further drawing.
The present invention provides direct-use poly(trimethylene terephthalate) yarns that are fully oriented spun yarns which may be used in textile fabrics without drawing or annealing, i.e., heat-setting.
The present invention comprises a process for spinning a direct-use yarn, comprising extruding a polyester polymer through a spinneret to form non-round filaments at a spinning speed less than 4500 mpm and a temperature between about 255xc2x0 C. and about 275xc2x0 C., wherein said polymer comprises at least 85 mole % poly(trimethylene terephthalate) wherein at least 85 mole % of repeating units consist of trimethylene units, and wherein said polymer has an intrinsic viscosity of at least 0.70 dl/g. Preferably, the spinning temperature is about 260xc2x0 C.-about 270xc2x0 C.
Preferably, the direct-use yarn is characterized by a boil off shrinkage of less than 15%.
Preferably, an individual filament in the plurality of non-round filaments is characterized by:                                                         a              )                        ⁢                          xe2x80x83                        ⁢            0.5                    ≤                                    A              1                                      A              2                                ≤          0.95                ;                  xe2x80x83                ⁢        and                                                                    b              )                        ⁢                          xe2x80x83                        ⁢                          A              2                                =                                    P              1              2                                      4              ⁢              π                                      ,            
wherein A1 is an area of a cross-section of the individual filament, P1 is a perimeter of said cross-section of the individual filament, and A2 is a maximum area of a cross-section having a perimeter P1. In one preferred embodiment, 0.6xe2x89xa6A1/A2xe2x89xa60.95. Preferably, at least 65% of the filaments of the yarn meet the conditions. More preferably, at least 70% of the filaments of the yarn meet the conditions. Even more preferably, at least 90% of the filaments of the yarn meet the conditions.
Preferably, on average the individual filaments in the yarn meet the conditions.
Preferably, the yarn filaments have deniers of 0.35 dpf-10 dpf. Preferably, the yarn has a denier of 20-300. Preferably, the poly(trimethylene terephthalate) has an IV of 0.8 dl/g-1.5 dl/g.
A direct-use yarn, is a yarn that is not drawn or annealed in a separate processing step.
The present invention also is directed to a direct-use yarn made from a polyester polymer melt-extruded at a spinning temperature between about 255xc2x0 C. and about 275xc2x0 C. and a spinning speed less than 4500 mpm, wherein said polymer comprises at least 85 mole % poly(trimethylene terephthalate) wherein at least 85 mole % of repeating units consist of trimethylene units, and wherein said polymer has an intrinsic viscosity of at least 0.70 dl/g, and wherein said direct-use yarn comprises a plurality of non-round filaments. Preferably, the spinning temperature is about 260xc2x0 C.-about 270xc2x0 C.
Preferably, the direct-use yarn is characterized by a boil off shrinkage of less than 15%.
Preferably, an individual filament in the plurality of non-round filaments is characterized by:                                                         a              )                        ⁢                          xe2x80x83                        ⁢            0.5                    ≤                                    A              1                                      A              2                                ≤          0.95                ;                  xe2x80x83                ⁢        and                                                                    b              )                        ⁢                          xe2x80x83                        ⁢                          A              2                                =                                    P              1              2                                      4              ⁢              π                                      ,            
wherein A1 is an area of a cross-section of the individual filament, P1 is a perimeter of said cross-section of the individual filament, and A2 is a maximum area of a cross-section having a perimeter P1. In one preferred embodiment, 0.6xe2x89xa6A1/A2xe2x89xa60.95. Preferably, at least 65% of the filaments of the yarn meet the conditions. More preferably, at least 70% of the filaments of the yarn meet the conditions. Even more preferably, at least 90% of the filaments of the yarn meet the conditions.
Preferably, on average the individual filaments in the yarn meet the conditions.
Preferably, the yarn filaments have deniers of 0.35 dpf-10 dpf. Preferably, the yarn has a denier of 20-300. Preferably, the poly(trimethylene terephthalate) has an IV of 0.8 dl/g-1.5 dl/g.
A direct-use yarn is a yarn that is not drawn or annealed in a separate processing step.
Preferably, at least 70% of the filaments of the yarn meet the conditions, the filaments of the yarn have deniers of 0.5 dpf to 7 dpf, the yarn has a denier of 30-200, and the direct-use yarn is characterized by a boil off shrinkage of less than 15%. More preferably, on average the individual filaments in the yarn meet the conditions and the poly(trimethylene terephthalate) has an IV of 0.8 dl/g-1.5 dl/g.
A direct-use yarn of has not and is not drawn or annealed.
The invention is further directed to process of preparing a fabric comprising:
(a) spinning a direct-use yarn as claimed in claim 1, and
(b) weaving or knitting the yarn into a fabric.
In this process, the yarn is fully oriented during spinning and is not drawn or annealed to orient the yarn after spinning.